JP4446991B2

JP4446991B2 - Method for producing acrylonitrile-based precursor fiber for carbon fiber

Info

Publication number: JP4446991B2
Application number: JP2006258806A
Authority: JP
Inventors: 徹間鍋; 光夫浜田; 仁子泉; 和宣角谷
Original assignee: Mitsubishi Chemical Corp; Mitsubishi Rayon Co Ltd
Current assignee: Mitsubishi Chemical Corp; Mitsubishi Rayon Co Ltd
Priority date: 2002-11-22
Filing date: 2006-09-25
Publication date: 2010-04-07
Anticipated expiration: 2023-09-08
Also published as: JP2007023476A

Description

本発明は、各種の複合材料において補強繊維材料として利用される炭素繊維束、特に強度発現性に優れる炭素繊維束、その炭素繊維用アクリロニトリル系前駆体繊維及びその製造方法に関する。 The present invention relates to a carbon fiber bundle used as a reinforcing fiber material in various composite materials, in particular, a carbon fiber bundle excellent in strength development, an acrylonitrile-based precursor fiber for the carbon fiber, and a method for producing the same.

従来、アクリル系繊維を前駆体とする炭素繊維はその優れた力学的性質により、航空宇宙用途を始め、スポーツ、レジャー用途の高性能複合材の補強繊維素材として広い範囲で利用されている。さらに、産業用途への広がりが進む中で、炭素繊維のさらなる高性能化が求められている。 Conventionally, carbon fibers having acrylic fibers as precursors are widely used as reinforcing fiber materials for high-performance composite materials for aerospace use, sports and leisure use due to their excellent mechanical properties. Furthermore, further expansion of the performance of carbon fibers is demanded as the spread to industrial applications progresses.

こうした要求に対し、特許文献１、特許文献２、特許文献３では炭素繊維の表面平滑性を制御することで炭素繊維複合材の性能を向上させる方法が提案されている。 In response to such demands, Patent Document 1, Patent Document 2, and Patent Document 3 propose a method for improving the performance of the carbon fiber composite material by controlling the surface smoothness of the carbon fiber.

しかし、炭素繊維は直径十数μｍ以下と非常に細いので、繊維表面の曲率が非常に大きい割に表面の凹凸は非常に微細であること、繊維断面が円形でない場合は繊維表面の曲率が複数あること、そして、微細な区間で測られた平滑性は必ずしも繊維全体で一様でないことから、測定値の平均値で表される表面平滑性に十分な信頼性がない場合があり、そのため、測定された表面平滑性と炭素繊維及び複合材料の性能との関係が必ずしも一致しない場合があった。 However, since carbon fiber is very thin with a diameter of tens of μm or less, the surface roughness is very fine for a very large fiber surface curvature, and if the fiber cross section is not circular, the fiber surface has multiple curvatures. Because the smoothness measured in a fine section is not necessarily uniform throughout the fiber, there may not be sufficient reliability for the surface smoothness represented by the average value of the measured values. In some cases, the relationship between the measured surface smoothness and the performance of the carbon fiber and the composite material does not always match.

さらに、特許文献３では、高強度炭素繊維を得る方法として、湿式紡糸法により得られる前駆体繊維の湿熱延伸倍率を最も好ましい範囲として２倍以下にする技術が提案されている。 Furthermore, in Patent Document 3, as a method for obtaining high-strength carbon fibers, a technique for setting the wet heat draw ratio of precursor fibers obtained by a wet spinning method to a most preferable range of 2 times or less is proposed.

しかし、ポリマー組成、紡糸原液溶媒、紡浴条件等の条件が異なった場合、適応できないことがあり、生産されている種々の品種に応用できないこともあった。また、この方法では乾燥緻密化前の延伸倍率が低いために、生産性を変更しないとした場合、乾燥緻密化後の延伸倍率を通常に比べ非常に大きくする必要がある。こうした場合、糸条全体の切断、あるいは全切断までは行かないものの部分的な糸の切断が発生し、毛羽が発生し品位の低下、紡糸及び焼成工程での工程通過性の低下を招くことがあり、実生産のためには優れた方法とはいえない。 However, when the conditions such as the polymer composition, the spinning solution solvent, and the spinning bath conditions are different, it may not be applicable and may not be applicable to various varieties produced. In this method, since the stretch ratio before dry densification is low, if the productivity is not changed, it is necessary to make the stretch ratio after dry densification much larger than usual. In such a case, cutting of the entire yarn, or partial cutting of the yarn that does not go until full cutting occurs, fluffing occurs, resulting in deterioration of quality, and deterioration of processability in spinning and firing processes. Yes, it is not an excellent method for actual production.

特許文献４では、ねじり弾性率を向上させる方法として、単繊維表層部に異種元素を含有させ、単繊維中心部よりも結晶性の低い領域を作り出す技術が提案されている。 In Patent Document 4, as a method for improving the torsional elastic modulus, a technique is proposed in which a dissimilar element is included in the single fiber surface layer portion to create a region having lower crystallinity than the single fiber center portion.

しかし、ねじり強度の向上については言及されておらず、異種元素を混入させることで、逆にねじり強度の低下をもたらす可能性があった。
特公昭５２−２４１３０号公報特開平１１−２１７７３４号公報特開２０００−１６０４３６号公報特開平９−１７０１７０号公報 However, the improvement of torsional strength is not mentioned, and mixing of different elements may cause a decrease in torsional strength.
Japanese Patent Publication No. 52-24130 JP-A-11-217734 JP 2000-160436 A JP-A-9-170170

本発明の課題は、用途に応じた種々の複合材において優れた特性を実現し得る炭素繊維束、その前駆体繊維、及びその製造方法を提供することである。 The subject of this invention is providing the carbon fiber bundle which can implement | achieve the outstanding characteristic in the various composite materials according to a use, its precursor fiber, and its manufacturing method.

本発明者らは、上記課題を解決するため鋭意研究の結果、本発明に至った。 As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.

本発明は、トータル延伸倍率とポリアクリロニトリルの（１００）反射から得られる結晶領域サイズが次式を満たす炭素繊維用アクリロニトリル系前駆体繊維の製造方法に関する。 The present invention is crystal area size obtained from (100) reflection of total draw ratio and polyacrylonitrile method of manufacturing a carbon-containing fibers for acrylonitrile based precursor fiber that meets the following equation.

本発明により、得られる前駆体繊維のポリアクリロニトリルの（１００）反射から得られる結晶領域サイズと、トータル延伸倍率とが前記式を満たす炭素繊維用アクリロニトリル系前駆体繊維の製造方法であって、
溶剤と該溶剤に溶解したアクリロニトリル系重合体とを含む紡糸原液を紡糸して凝固糸を得る紡糸工程、該凝固糸を湿熱延伸する湿熱延伸工程、該延伸した糸を油剤処理する油剤処理工程、該油剤処理した糸を乾燥緻密化する乾燥緻密化工程を有し、トータル延伸倍率を１２倍以下、湿熱延伸倍率を、３倍以上かつ湿熱延伸糸膨潤度が最大値になるときの延伸倍率以下とする炭素繊維用アクリロニトリル系前駆体繊維の製造方法が提供される。
また本発明により、得られる前駆体繊維のポリアクリロニトリルの（１００）反射から得られる結晶領域サイズと、トータル延伸倍率とが前記式を満たす炭素繊維用アクリロニトリル系前駆体繊維の製造方法であって、
溶剤と該溶剤に溶解したアクリロニトリル系重合体とを含む紡糸原液を紡糸して凝固糸を得る紡糸工程、該凝固糸を湿熱延伸する湿熱延伸工程、該延伸した糸を油剤処理する油剤処理工程、該油剤処理した糸を乾燥緻密化する乾燥緻密化工程を有し、トータル延伸倍率を１２倍以下、湿熱延伸倍率を、３倍以上かつ湿熱延伸糸膨潤度が飽和点に達するときの延伸倍率以下とする炭素繊維用アクリロニトリル系前駆体繊維の製造方法が提供される。 According to the present invention, the crystal region size obtained from the (100) reflection of polyacrylonitrile of the obtained precursor fiber and the total draw ratio satisfy the above formula, and the method for producing acrylonitrile-based precursor fiber for carbon fiber,
A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, It has a drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the draw ratio when the wet heat draw yarn swelling degree is the maximum value or less A method for producing acrylonitrile-based precursor fiber for carbon fiber is provided.
Further, according to the present invention, the crystal region size obtained from the (100) reflection of polyacrylonitrile of the obtained precursor fiber and the total draw ratio satisfy the above formula, and the method for producing acrylonitrile-based precursor fiber for carbon fiber,
A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, It has a drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the draw ratio when the wet heat draw yarn swelling degree reaches the saturation point or less A method for producing acrylonitrile-based precursor fiber for carbon fiber is provided.

本発明により、得られる前駆体繊維のポリアクリロニトリルの（１００）反射から得られる結晶領域サイズと、トータル延伸倍率とが前記式を満たす炭素繊維用アクリロニトリル系前駆体繊維の製造方法であって、
溶剤と該溶剤に溶解したアクリロニトリル系重合体とを含む紡糸原液を紡糸して凝固糸を得る紡糸工程、該凝固糸を湿熱延伸する湿熱延伸工程、該延伸した糸を油剤処理する油剤処理工程、該油剤処理した糸を乾燥緻密化する乾燥緻密化工程を有し、トータル延伸倍率を１２倍以下、湿熱延伸倍率を、３倍以上かつ湿熱延伸糸の平均細孔半径が最大値になるときの延伸倍率以下とする炭素繊維用アクリロニトリル系前駆体繊維の製造方法が提供される。
また本発明により、得られる前駆体繊維のポリアクリロニトリルの（１００）反射から得られる結晶領域サイズと、トータル延伸倍率とが前記式を満たす炭素繊維用アクリロニトリル系前駆体繊維の製造方法であって、
溶剤と該溶剤に溶解したアクリロニトリル系重合体とを含む紡糸原液を紡糸して凝固糸を得る紡糸工程、該凝固糸を湿熱延伸する湿熱延伸工程、該延伸した糸を油剤処理する油剤処理工程、該油剤処理した糸を乾燥緻密化する乾燥緻密化工程を有し、トータル延伸倍率を１２倍以下、湿熱延伸倍率を、３倍以上かつ湿熱延伸糸の平均細孔半径が飽和点に達するときの延伸倍率以下とする炭素繊維用アクリロニトリル系前駆体繊維の製造方法が提供される。 According to the present invention, the crystal region size obtained from the (100) reflection of polyacrylonitrile of the obtained precursor fiber and the total draw ratio satisfy the above formula, and the method for producing acrylonitrile-based precursor fiber for carbon fiber,
A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, a dry densification process of drying densified yarn treated oil agent, the total draw ratio 12 times or less, the wet heat stretching ratio, average pore radius at which becomes a maximum value of 3 times or more and wet heat drawn yarn A method for producing an acrylonitrile-based precursor fiber for carbon fiber having a draw ratio or less is provided.
Further, according to the present invention, the crystal region size obtained from the (100) reflection of polyacrylonitrile of the obtained precursor fiber and the total draw ratio satisfy the above formula, and the method for producing acrylonitrile-based precursor fiber for carbon fiber,
A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, A drying densification step of drying and densifying the oil-treated yarn, a total draw ratio of 12 times or less, a wet heat draw ratio of 3 times or more, and an average pore radius of the wet heat draw yarn reaches a saturation point A method for producing an acrylonitrile-based precursor fiber for carbon fiber having a draw ratio or less is provided.

本発明により、得られる前駆体繊維のポリアクリロニトリルの（１００）反射から得られる結晶領域サイズと、トータル延伸倍率とが前記式を満たす炭素繊維用アクリロニトリル系前駆体繊維の製造方法であって、
溶剤と該溶剤に溶解したアクリロニトリル系重合体とを含む紡糸原液を紡糸して凝固糸を得る紡糸工程、該凝固糸を湿熱延伸する湿熱延伸工程、該延伸した糸を油剤処理する油剤処理工程、該油剤処理した糸を乾燥緻密化する乾燥緻密化工程を有し、トータル延伸倍率を１２倍以下、湿熱延伸倍率を、３倍以上かつ乾燥緻密化直後の繊維配向度が最大値になるときの延伸倍率以下とする炭素繊維用アクリロニトリル系前駆体繊維の製造方法が提供される。
また本発明により、得られる前駆体繊維のポリアクリロニトリルの（１００）反射から得られる結晶領域サイズと、トータル延伸倍率とが前記式を満たす炭素繊維用アクリロニトリル系前駆体繊維の製造方法であって、
溶剤と該溶剤に溶解したアクリロニトリル系重合体とを含む紡糸原液を紡糸して凝固糸を得る紡糸工程、該凝固糸を湿熱延伸する湿熱延伸工程、該延伸した糸を油剤処理する油剤処理工程、該油剤処理した糸を乾燥緻密化する乾燥緻密化工程を有し、トータル延伸倍率を１２倍以下、湿熱延伸倍率を、３倍以上かつ乾燥緻密化直後の繊維配向度が飽和点に達するときの延伸倍率以下とする炭素繊維用アクリロニトリル系前駆体繊維の製造方法が提供される。 According to the present invention, the crystal region size obtained from the (100) reflection of polyacrylonitrile of the obtained precursor fiber and the total draw ratio satisfy the above formula, and the method for producing acrylonitrile-based precursor fiber for carbon fiber,
A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, A drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the fiber orientation degree immediately after the dry densification becomes the maximum value A method for producing an acrylonitrile-based precursor fiber for carbon fiber having a draw ratio or less is provided.
Further, according to the present invention, the crystal region size obtained from the (100) reflection of polyacrylonitrile of the obtained precursor fiber and the total draw ratio satisfy the above formula, and the method for producing acrylonitrile-based precursor fiber for carbon fiber,
A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, A drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the fiber orientation degree immediately after the dry densification reaches the saturation point A method for producing an acrylonitrile-based precursor fiber for carbon fiber having a draw ratio or less is provided.

上記炭素繊維用アクリロニトリル系前駆体繊維の製造方法において、前記溶剤がジメチルアセトアミドあるいはジメチルホルムアミドであり、前記湿熱延伸を行う際の湿熱延伸糸膨潤度が１２０％以下であることが好ましい。 In the method for producing an acrylonitrile-based precursor fiber for carbon fiber, it is preferable that the solvent is dimethylacetamide or dimethylformamide, and the wet-heat drawn yarn swelling degree when the wet-heat drawing is performed is 120% or less.

本発明によれば、用途に応じた種々の複合材において優れた特性を実現し得る炭素繊維束とその製造に好適な前駆体繊維が提供され、さらにこの前駆体繊維を好適に製造することのできる製造方法が提供される。 According to the present invention, a carbon fiber bundle capable of realizing excellent characteristics in various composite materials according to applications and a precursor fiber suitable for the production thereof are provided, and further, the precursor fiber can be suitably produced. A possible manufacturing method is provided.

本発明の炭素繊維束は、単繊維ねじり弾性率に対する単繊維ねじり強度の比（単繊維ねじり強度（ＧＰａ）／単繊維ねじり弾性率（ＧＰａ））が０．１以上である炭素繊維の単繊維を７０質量％以上含む炭素繊維束である。 The carbon fiber bundle of the present invention is a single fiber of carbon fiber having a ratio of single fiber torsional strength to single fiber torsional elastic modulus (single fiber torsional strength (GPa) / single fiber torsional elastic modulus (GPa)) of 0.1 or more. Is a carbon fiber bundle containing 70% by mass or more.

上記比が０．１以上となる単繊維が７０％未満の場合、ねじり弾性率に対するねじり強度が低い炭素繊維単繊維の割合が多くなり、複合材料とした場合に、複雑な応力に対しての強度が著しく低下する。同様の観点から、上記比が０．０９以上である炭素繊維の短繊維を９０質量％以上含むことが好ましい。単繊維ねじり強度（ＧＰａ）／単繊維ねじり弾性率（ＧＰａ）の値が０．１以上を示す炭素繊維単繊維の割合は、大きければ大きいほど好ましい。 When the ratio of single fibers having a ratio of 0.1 or more is less than 70%, the ratio of carbon fiber single fibers having low torsional strength with respect to the torsional elastic modulus increases, and in the case of a composite material, The strength is significantly reduced. From the same viewpoint, it is preferable that 90% by mass or more of carbon fiber short fibers having the above ratio of 0.09 or more are included. The larger the ratio of carbon fiber single fibers, the value of single fiber torsional strength (GPa) / single fiber torsional elastic modulus (GPa) is 0.1 or more, the more preferable.

また本発明は、トータル延伸倍率とポリアクリロニトリルの（１００）反射から得られる結晶領域サイズが次式を満たすことを特徴とする炭素繊維用アクリロニトリル系前駆体繊維である。尚、ここで言うトータル延伸倍率とは、乾燥緻密化前に凝固糸を延伸する延伸倍率と乾燥緻密化後の延伸倍率を掛け合わせた値であり、紡糸の最終ロール速度を凝固糸の引き取り速度で割った値でも同じである。 Moreover, this invention is an acrylonitrile type | system | group precursor fiber for carbon fibers characterized by the crystal | crystallization area | region size obtained from a total draw ratio and the (100) reflection of polyacrylonitrile satisfy | filling following Formula. The total draw ratio referred to here is a value obtained by multiplying the draw ratio for drawing the coagulated yarn before dry densification and the draw ratio after dry densification, and the final roll speed of spinning is the take-up speed of the coagulated yarn. The same is true for the value divided by.

かかる炭素繊維用アクリロニトリル系前駆体繊維は、後述する本発明の製造方法により好適に得ることができ、かかる本発明の炭素繊維用アクリロニトリル系前駆体繊維を焼成することによって上述した本発明の炭素繊維束を好適に得ることができる。上記式が満たされると、本発明の炭素繊維束を好適に得ることができ、延伸により繊維内の結晶領域、もしくは結晶領域と非晶領域の界面が破壊されることを防止し、焼成時にグラファイト結晶網面内およびその付近に欠陥が生じて炭素繊維性能が著しく低下することを防止することができる。 Such an acrylonitrile-based precursor fiber for carbon fiber can be suitably obtained by the production method of the present invention described later, and the carbon fiber of the present invention described above by firing the acrylonitrile-based precursor fiber for carbon fiber of the present invention. A bundle can be suitably obtained. When the above formula is satisfied, the carbon fiber bundle of the present invention can be suitably obtained, and the crystalline region in the fiber or the interface between the crystalline region and the amorphous region is prevented from being broken by stretching, and graphite is fired during firing. It is possible to prevent the carbon fiber performance from being remarkably deteriorated due to defects in the crystal network surface and the vicinity thereof.

以下に本発明の炭素繊維束及び炭素繊維用アクリロニトリル系前駆体繊維の製造方法について詳しく説明する。 Below, the manufacturing method of the carbon fiber bundle of this invention and the acrylonitrile type | system | group precursor fiber for carbon fibers is demonstrated in detail.

本発明の炭素繊維用アクリロニトリル系前駆体繊維に用いるアクリロニトリル系重合体としてはアクリロニトリルのホモポリマー及び／又は他のモノマーとの共重合体を用いることができる。この場合、炭素化を良好に行う目的で共重合体中のアクリロニトリル組成は９０質量％以上であることが好ましく、炭素繊維にした時の共重合成分に起因する欠陥点を少なくし、炭素繊維の品位並びに性能を向上させる目的からアクリロニトリルが９５質量％以上であることがより好ましい。 As the acrylonitrile polymer used for the acrylonitrile precursor fiber for carbon fiber of the present invention, a homopolymer of acrylonitrile and / or a copolymer with another monomer can be used. In this case, the acrylonitrile composition in the copolymer is preferably 90% by mass or more for the purpose of good carbonization, and the number of defects caused by the copolymer component when the carbon fiber is made is reduced. In order to improve the quality and performance, acrylonitrile is more preferably 95% by mass or more.

アクリロニトリル系重合体の共重合成分モノマーとしては、特に制限は無いが、例えばアクリル酸メチル、アクリル酸エチル、アクリル酸イソプロピル、アクリル酸ｎ−ブチル、アクリル酸２−エチルヘキシル、アクリル酸２−ヒドロキシエチル、アクリル酸ヒドロキシプロピルなどに代表されるアクリル酸エステル類；メタクリル酸メチル、メタクリル酸エチル、メタクリル酸イソプロピル、メタクリル酸ｎ−ブチル、メタクリル酸ｎ−ヘキシル、メタクリル酸シクロヘキシル、メタクリル酸ラウリル、メタクリル酸２−ヒドロキシエチル、メタクリル酸ヒドロキシプロピル、メタクリル酸ジエチルアミノエチルなどに代表されるメタクリル酸エステル類；アクリル酸、メタクリル酸、マレイン酸、イタコン酸、アクリルアミド、Ｎ−メチロールアクリルアミド、ジアセトンアクリルアミド、スチレン、ビニルトルエン、酢酸ビニル、塩化ビニル、塩化ビニリデン、臭化ビニル、臭化ビニリデン、フッ化ビニル、フッ化ビニリデンなどの不飽和モノマー類；ｐ−スルホフェニルメタリルエーテル、メタリルスルホン酸、アリルスルホン酸、スチレンスルホン酸、２−アクリルアミド−２−メチルプロパンスルホン酸及びこれらのアルカリ金属塩などが挙げられる。 The copolymer component monomer of the acrylonitrile-based polymer is not particularly limited, but for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, Acrylic esters represented by hydroxypropyl acrylate, etc .; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, 2-methacrylic acid 2- Methacrylic acid esters represented by hydroxyethyl, hydroxypropyl methacrylate, diethylaminoethyl methacrylate, etc .; acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide, N-methyl Unsaturated monomers such as vinyl acrylamide, diacetone acrylamide, styrene, vinyl toluene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, vinyl fluoride, vinylidene fluoride; p-sulfophenylmethallyl ether , Methallylsulfonic acid, allylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and alkali metal salts thereof.

アクリロニトリル系重合体の共重合成分モノマーとして、炭素化工程における環化反応を促進する目的でカルボン酸基を有するモノマーやアクリルアミド系モノマーを用いることが好ましい。このようなカルボン酸基を有するモノマーとしては、メタクリル酸やイタコン酸が好ましい。又、アクリルアミド系モノマーとしてはアクリルアミドが好ましい。そして、溶剤に対する溶解性の向上、凝固糸の緻密性の向上の観点から、アクリルアミドは共重合体に１質量％以上含まれることが好ましい。従って、この場合必然的にアクリロニトリルは９９質量％以下が好ましい範囲となる。凝固糸の緻密性については、特に、湿式紡糸であるか乾湿式紡糸であるかに関わらず、取り得る可能なほとんどの凝固浴条件で凝固糸にボイドの発生がないために、品種に応じた任意の凝固浴条件で優れた炭素繊維を実現することが可能である。アクリルアミドの含有量の上限は特に限定はされないが、好ましくは４質量％未満である。 As the copolymerization component monomer of the acrylonitrile-based polymer, it is preferable to use a monomer having a carboxylic acid group or an acrylamide-based monomer for the purpose of promoting the cyclization reaction in the carbonization step. As the monomer having such a carboxylic acid group, methacrylic acid and itaconic acid are preferable. As the acrylamide monomer, acrylamide is preferable. And from a viewpoint of the improvement of the solubility with respect to a solvent, and the improvement of the compactness of a coagulated yarn, it is preferable that 1 mass% or more of acrylamide is contained in a copolymer. Accordingly, in this case, acrylonitrile inevitably has a preferable range of 99% by mass or less. Concerning the compactness of the coagulated yarn, it depends on the type of the product, since there is no void formation in the coagulated yarn under most possible coagulation bath conditions, regardless of whether it is wet spinning or dry wet spinning. It is possible to realize excellent carbon fibers under arbitrary coagulation bath conditions. The upper limit of the acrylamide content is not particularly limited, but is preferably less than 4% by mass.

原料に用いるアクリロニトリル系重合体の重合方法には、溶液重合、懸濁重合など、公知の重合方法の何れをも採用することができる。重合された共重合体から、未反応モノマーや重合触媒残渣、その他の不純物類を極力除く処理を施すことが好ましい。また、前駆体繊維紡糸での延伸性や炭素繊維の性能発現性等の点から、共重合体の重合度は、極限粘度〔η〕が１．０以上が好ましく、特に１．４以上の範囲が好ましい。重合度が高いと溶媒への溶解や製糸が困難となる傾向があるので、極限粘度〔η〕は、４．０を超えない範囲のものが好ましく利用される。 Any known polymerization method such as solution polymerization or suspension polymerization can be employed as the polymerization method of the acrylonitrile-based polymer used as the raw material. It is preferable to subject the polymerized copolymer to a treatment that removes unreacted monomers, polymerization catalyst residues, and other impurities as much as possible. In addition, from the viewpoints of stretchability in precursor fiber spinning, performance of carbon fiber, and the like, the degree of polymerization of the copolymer is preferably 1.0 or more, and particularly preferably in the range of 1.4 or more. Is preferred. When the degree of polymerization is high, dissolution in a solvent and spinning tend to be difficult, so that the intrinsic viscosity [η] is preferably in a range not exceeding 4.0.

次に、アクリロニトリル系共重合体、好ましくは不純物の除去処理を施した前記共重合体を溶剤に溶解し、紡糸原液とする。溶剤としては、ジメチルアセトアミド、ジメチルスルホキシド、ジメチルホルムアミドなどの有機溶剤や、塩化亜鉛、チオシアン酸ナトリウムなどの無機化合物の水溶液が使用できる。作製される繊維中に金属を含有せず、また、工程が簡略化される点で有機溶剤が好ましい。その中でも凝固糸及び湿熱延伸糸の緻密性が高いという点で、ジメチルアセトアミドあるいはジメチルホルムアミドを溶剤に用いることがより好ましい。 Next, the acrylonitrile-based copolymer, preferably the copolymer subjected to the impurity removal treatment, is dissolved in a solvent to obtain a spinning dope. As the solvent, organic solvents such as dimethylacetamide, dimethylsulfoxide, dimethylformamide, and aqueous solutions of inorganic compounds such as zinc chloride and sodium thiocyanate can be used. An organic solvent is preferable in that the fiber to be produced does not contain a metal and the process is simplified. Among them, it is more preferable to use dimethylacetamide or dimethylformamide as a solvent in terms of high density of the coagulated yarn and wet heat drawn yarn.

紡糸した際、緻密な凝固糸を得るためには、紡糸原液として、ある程度以上のポリマー濃度を有する重合体溶液を使用することが好ましい。具体的には、紡糸原液中の重合体濃度は、好ましくは１７質量％以上、より好ましくは１９質量％以上の範囲とする。用いる重合体の重合度にもよるが、適正な粘度・流動性を有するものとするため、重合体濃度は、２５質量％を超えない範囲が好ましい。 In order to obtain a dense coagulated yarn upon spinning, it is preferable to use a polymer solution having a polymer concentration of a certain level or more as the spinning dope. Specifically, the polymer concentration in the spinning dope is preferably 17% by mass or more, more preferably 19% by mass or more. Although it depends on the degree of polymerization of the polymer to be used, the polymer concentration is preferably within a range not exceeding 25% by mass in order to have appropriate viscosity and fluidity.

炭素繊維用アクリロニトリル系前駆体繊維の紡糸法は、湿式紡糸法か乾湿式紡糸法が好ましいが乾式紡糸法でも良い。湿式紡糸法、乾湿式紡糸法は用途に応じ使い分けられる。 The spinning method of the acrylonitrile-based precursor fiber for carbon fiber is preferably a wet spinning method or a dry wet spinning method, but may be a dry spinning method. The wet spinning method and the dry and wet spinning method are properly used depending on the application.

紡糸工程は、先ず、前記の紡糸原液をノズル孔より凝固浴中に吐出し凝固糸とする。ノズル孔の形状に制限はないが、円形が一般的に使用される。凝固浴は、まず作製される凝固糸引き取りに十分な余裕がある条件に設定する。そして、凝固糸の断面形状が、円形、空豆形、楕円形など炭素繊維の用途に応じた形状になるように、凝固浴に含まれる溶剤濃度、温度を設定する。 In the spinning step, first, the spinning solution is discharged from a nozzle hole into a coagulation bath to obtain a coagulated yarn. The shape of the nozzle hole is not limited, but a circular shape is generally used. First, the coagulation bath is set to a condition with sufficient margin for taking up the coagulated yarn to be produced. Then, the concentration and temperature of the solvent contained in the coagulation bath are set so that the cross-sectional shape of the coagulated yarn has a shape corresponding to the use of the carbon fiber, such as a circle, an empty bean shape, or an oval shape.

凝固浴には、紡糸原液に用いられる溶剤を含む水溶液が好適に使用される。ノズル孔より吐出される紡糸原液が所望の繊維径の凝固糸となるように、含まれる溶剤の濃度を調節する。使用する溶剤の種類にも依存するが、例えば、ジメチルアセトアミドあるいはジメチルホルムアミドを使用する場合、その濃度は５０〜８０質量％に選択することが好ましい。 For the coagulation bath, an aqueous solution containing a solvent used for the spinning dope is preferably used. The concentration of the solvent contained is adjusted so that the spinning dope discharged from the nozzle hole becomes a coagulated yarn having a desired fiber diameter. Although depending on the type of solvent to be used, for example, when dimethylacetamide or dimethylformamide is used, the concentration is preferably selected to be 50 to 80% by mass.

また、凝固浴の温度は、凝固糸の緻密性の観点からは温度が低い方が好ましい。しかしながら、湿式紡糸の場合、凝固浴の温度を下げると凝固糸の引き取り速度が低下し、全体的な生産性が低下する点を考慮し、通常、好ましくは５０℃以下、より好ましくは２０℃以上４０℃以下の範囲に選択する。 The temperature of the coagulation bath is preferably lower from the viewpoint of the density of the coagulated yarn. However, in the case of wet spinning, considering that the coagulated yarn take-off speed decreases and the overall productivity decreases when the temperature of the coagulation bath is lowered, it is usually preferably 50 ° C. or less, more preferably 20 ° C. or more. Select in the range below 40 ° C.

上記凝固糸は続いて湿熱延伸を施される。本発明で言う湿熱延伸とは該凝固糸が乾燥緻密化までになされる延伸のことを指す。従って、湿熱延伸倍率とは乾燥緻密化を行うロール速度と凝固糸を引き取るロール速度との比で定義され、湿熱延伸糸とは乾燥緻密化直前の糸を言う。湿熱延伸方法としては、空中での延伸、水、溶媒／水混合液、グリセリンなどの液体媒体中での延伸及び加圧あるいは常圧の水蒸気中での延伸などの方法を任意の順番で組み合わせてよい。途中に緩和工程を含んでも良い。但し、乾燥緻密化までに含まれている溶剤の洗浄を完了する観点から、温水中での延伸倍率が半分以上占めるのが好ましい。例えば、湿熱延伸倍率が３倍の場合は温水中の延伸は１．７（＝√３）倍以上が好ましい。さらに、温水温度は単糸同士が融着しない範囲で、できるだけ高温にすることが効果的である。この観点から、延伸浴の温度は７０℃以上の高温とすることが好ましい。また、温水の多段延伸の場合は、その最終浴を９０℃以上の高温にすることが好ましい。また、この湿熱延伸に先立って、温水中で溶剤の洗浄を行っても良い。本発明者らは、湿熱延伸倍率が高くなるにつれ湿熱延伸糸の膨潤度が高くなり、ある延伸倍率で膨潤度が最大あるいは飽和になることを見出した。そして、湿熱延伸糸の平均細孔半径や乾燥緻密化直後の糸の繊維配向度も同様の関係であることを見出した。これらは、湿熱延伸倍率がある値以上になると湿熱延伸糸の膨潤度や平均細孔半径はほとんど変化しないか小さくなり緻密性が向上したように見えるが、実際は配向の向上しない延伸が行われており、繊維内部構造の破壊が起こったことを示している。この破壊が炭素繊維の欠陥の元となり性能の低下を招くのである。特に、ねじり物性ではこれが顕著に現れ、ねじり弾性率に対するねじり強度を大きく低下させる。尚、乾燥緻密化直後の糸とは、湿熱延伸糸を後述する油剤付与及びそれに続く乾燥緻密化処理を行い、その後の延伸を行わない段階の糸のことである。 The coagulated yarn is subsequently subjected to wet heat drawing. The wet heat stretching referred to in the present invention refers to stretching performed until the coagulated yarn is dried and densified. Accordingly, the wet heat draw ratio is defined by the ratio of the roll speed at which dry densification is performed and the roll speed at which the coagulated yarn is taken up, and the wet heat draw yarn refers to a yarn immediately before dry densification. As the wet heat stretching method, stretching in the air, stretching in a liquid medium such as water, solvent / water mixture, glycerin and stretching in a water vapor under pressure or atmospheric pressure can be combined in any order. Good. A relaxation step may be included on the way. However, it is preferable that the draw ratio in warm water occupies more than half from the viewpoint of completing the washing of the solvent contained before drying and densification. For example, when the wet heat draw ratio is 3 times, the draw in warm water is preferably 1.7 (= √3) times or more. Furthermore, it is effective to make the hot water temperature as high as possible within a range where the single yarns are not fused. From this viewpoint, it is preferable that the temperature of the stretching bath is a high temperature of 70 ° C. or higher. Moreover, in the case of multistage stretching of warm water, it is preferable that the final bath has a high temperature of 90 ° C. or higher. Prior to the wet heat stretching, the solvent may be washed in warm water. The present inventors have found that as the wet heat draw ratio increases, the degree of swelling of the wet heat drawn yarn increases, and the degree of swelling becomes maximum or saturated at a certain draw ratio. It was also found that the average pore radius of the wet heat drawn yarn and the fiber orientation degree of the yarn immediately after dry densification have the same relationship. When the wet heat draw ratio exceeds a certain value, the swelling degree and average pore radius of the wet heat drawn yarn hardly change or become small, and it seems that the denseness is improved. This indicates that the destruction of the fiber internal structure has occurred. This destruction becomes a source of defects in the carbon fiber and causes a decrease in performance. In particular, this appears remarkably in the torsional physical properties, and greatly reduces the torsional strength with respect to the torsional elastic modulus. The yarn immediately after dry densification refers to a yarn at a stage where the wet heat stretched yarn is subjected to oil agent application described later and subsequent dry densification treatment, and no subsequent stretching is performed.

このような現象を防止するためには、湿熱延伸糸膨潤度、平均細孔半径、乾燥緻密化直後の配向度の内の少なくとも１つについて、その値が最大値あるいは飽和に達する延伸倍率以下になる湿熱延伸倍率を選ぶことが有効である。 In order to prevent such a phenomenon, at least one of the wet heat draw yarn swelling degree, the average pore radius, and the orientation degree immediately after dry densification, the value is below the draw ratio at which the value reaches the maximum value or saturation. It is effective to select a wet heat draw ratio.

湿熱延伸糸膨潤度、平均細孔半径及び乾燥緻密化直後の糸の繊維配向度が最大値あるいは飽和に達する湿熱延伸倍率は、当然、重合体組成、紡糸原液溶媒、紡浴条件等の条件に依り異なってくるので、条件ごとに上記各値の最大値あるいは飽和に達する湿熱延伸倍率を求めた後に、湿熱延伸倍率を設定することで本発明は達成される。上記各値の最大値あるいは飽和に達する湿熱延伸倍率は、湿熱延伸倍率０．２倍以上０．８倍以下ごとに各値を測定するのが好ましい。０．８倍より大きい場合は、正確に最大値あるいは飽和に達する湿熱延伸倍率を求めることができないことがある。０．２倍より小さい場合は、測定点が増え測定が煩雑になるだけである。尚、飽和点とは、横軸に湿熱延伸倍率、縦軸に測定値をとったとき測定点を結ぶ線分の傾きの絶対値が最大の傾きの１０分の１以下になった点とする。 The wet heat draw ratio of the wet heat draw yarn swelling degree, the average pore radius, and the fiber orientation degree of the yarn immediately after dry densification reaches the maximum value or the saturation naturally depends on the conditions such as the polymer composition, the spinning solution solvent, and the spinning bath conditions. Therefore, the present invention is achieved by setting the wet heat draw ratio after obtaining the maximum value of each of the above values or the wet heat draw ratio that reaches saturation for each condition. It is preferable that the wet heat draw ratio reaching the maximum value or saturation of each of the above values is measured for each wet heat draw ratio of 0.2 to 0.8 times. When it is larger than 0.8 times, the wet heat draw ratio that reaches the maximum value or saturation may not be obtained accurately. When it is smaller than 0.2 times, the number of measurement points increases and the measurement is only complicated. The saturation point is the point at which the absolute value of the slope of the line connecting the measurement points becomes 1/10 or less of the maximum slope when the horizontal axis represents the wet heat draw ratio and the vertical axis represents the measurement value. .

湿熱延伸倍率をより低い値に設定すると、乾燥緻密化後の延伸倍率をより大きくする必要があり紡糸工程通過性が相対的に悪くなる傾向がある。そのため、安定に生産するには、紡糸速度を遅くするなど生産性を落とす必要が生じる場合がある。かかる観点から、湿熱延伸倍率は１．５倍以上が好ましい。ただし、本発明では、特に、湿熱延伸倍率を３倍以上とする。
If the wet heat draw ratio is set to a lower value, it is necessary to increase the draw ratio after drying and densification, and the spinning process passability tends to be relatively poor. Therefore, in order to produce stably, it may be necessary to reduce productivity, for example, by lowering the spinning speed. From this viewpoint, the wet heat draw ratio is preferably 1.5 times or more. However, in the present invention, in particular, the wet heat draw ratio is set to 3 times or more.

このように乾燥緻密化前の延伸倍率を設定することで、本発明の炭素繊維及び炭素繊維用アクリロニトリル系前駆体繊維を得ることができ、重合体組成、紡糸原液溶媒、湿式あるいは乾湿式等の紡糸方式、紡浴条件、繊維断面形状、単糸繊度及び総繊度等の各条件に依らず、優れた複合材特性を実現し得る炭素繊維を得ることが可能となる。 Thus, by setting the draw ratio before dry densification, the carbon fiber of the present invention and the acrylonitrile precursor fiber for carbon fiber can be obtained, and the polymer composition, spinning solution solvent, wet or wet and dry etc. It is possible to obtain a carbon fiber that can realize excellent composite properties regardless of the spinning method, spinning bath conditions, fiber cross-sectional shape, single yarn fineness, total fineness, and the like.

湿熱延伸、洗浄後、繊維表面には、公知の方法によって油剤処理を施す。油剤の種類は特に限定されないが、アミノシリコン系界面活性剤が好適に使用される。この油剤処理後、乾燥緻密化が行われる。この乾燥緻密化の温度は、繊維のガラス転移温度を超える温度に選択する。ガラス転移温度は、繊維自体の状態が、実質的には含水状態から乾燥状態へと変化することによって異なることもあり、温度が１００〜２００℃程度の加熱ローラーを用いる方法が好ましい。 After wet heat drawing and washing, the fiber surface is treated with an oil agent by a known method. Although the kind of oil agent is not specifically limited, Aminosilicon type surfactant is used suitably. After this oil agent treatment, dry densification is performed. The drying densification temperature is selected to be above the glass transition temperature of the fiber. The glass transition temperature may differ depending on the state of the fiber itself changing from a water-containing state to a dry state, and a method using a heating roller having a temperature of about 100 to 200 ° C. is preferred.

乾燥緻密化後、再度延伸を行うことで、前駆体繊維を所望の繊維径とする後延伸工程を設けることが好ましい。この後延伸は、高温の加熱ローラー、熱盤などを利用する乾熱延伸、あるいは加圧スチームによるスチーム延伸など、繊維自体の状態を大きく変えない限り、種々の方式を用いることができる。また、多段で行うことも可能である。後延伸工程自体の延伸倍率は、乾燥緻密化の前に実施される延伸と前記乾燥緻密化の後に実施される後延伸工程と、これら全体として、所定の延伸倍率を達成するように、後延伸工程における延伸倍率は選択される。 It is preferable to provide a post-stretching step in which the precursor fiber is made to have a desired fiber diameter by performing stretching again after drying and densification. For this post-drawing, various methods can be used as long as the state of the fiber itself is not greatly changed, such as dry-heat drawing using a high-temperature heating roller or a hot platen, or steam drawing using pressurized steam. Also, it can be performed in multiple stages. The stretching ratio of the post-stretching process itself is the stretching performed before dry densification, the post-stretching process performed after the dry densification, and the post-stretching so as to achieve a predetermined stretch ratio as a whole. The draw ratio in the process is selected.

また、乾燥緻密化前の延伸倍率と後延伸倍率を合わせた合計延伸倍率は、繊維の配向性に優れ、優れた性能の炭素繊維を得る観点から好ましくは６倍以上、より好ましくは８倍以上とし、糸切れを良好に防止して優れた生産性を実現する観点から好ましくは２０倍以下、より好ましくは１５倍以下とする。ただし、本発明では、特に、合計延伸倍率を１２倍以下とする。 Moreover, the total draw ratio that combines the draw ratio before drying and densification is preferably 6 times or more, more preferably 8 times or more from the viewpoint of obtaining carbon fibers having excellent fiber orientation and excellent performance. From the viewpoint of satisfactorily preventing yarn breakage and realizing excellent productivity, it is preferably 20 times or less, more preferably 15 times or less. However, in the present invention, in particular, the total draw ratio is set to 12 times or less.

以上説明したように、溶剤とこの溶剤に溶解したアクリロニトリル系共重合体を含む紡糸原液を紡糸して凝固糸を得る紡糸工程、この凝固糸を湿熱延伸する湿熱延伸工程、延伸した糸を油剤処理する油剤処理工程、油剤処理した糸を乾燥緻密化する乾燥緻密化工程を有する炭素繊維用アクリロニトリル系前駆体繊維の製造方法において、湿熱延伸倍率を前述の範囲にすることにより、優れた炭素繊維用アクリロニトリル系前駆体繊維を得ることができる。 As described above, a spinning process in which a spinning stock solution containing a solvent and an acrylonitrile-based copolymer dissolved in the solvent is spun to obtain a coagulated yarn, a wet heat drawing process in which the coagulated yarn is wet-heat drawn, and the drawn yarn is treated with an oil agent. In the method for producing an acrylonitrile-based precursor fiber for carbon fiber having an oil agent treatment step and a dry densification step for drying and densifying the oil agent-treated yarn, by making the wet heat draw ratio within the above-mentioned range, an excellent for carbon fiber Acrylonitrile-based precursor fibers can be obtained.

この前駆体繊維を、耐炎化工程、炭素化工程など公知の技術により焼成し、アクリロニトリル系炭素繊維を得ることができる。 The precursor fiber can be baked by a known technique such as a flameproofing process or a carbonization process to obtain an acrylonitrile-based carbon fiber.

以下に、実施例により本発明をより具体的に説明する。ただし、実施例１、６および７は参考例である。なお、以下に述べる実施例は、本発明における最良の実施形態の一例であるものの、本発明は、これら実施例により限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples. However, Examples 1, 6 and 7 are reference examples. In addition, although the Example described below is an example of the best embodiment in this invention, this invention is not limited by these Examples.

本発明を記載する際に利用される、炭素繊維用アクリロニトリル系前駆体繊維及び炭素繊維の各種物性、具体的には、「膨潤度」、「平均細孔半径」、「配向度」、「結晶領域サイズ」、「ストランド強度、弾性率」ならびに「ねじり強度、弾性率」に関して、その評価方法を予め説明する。実施例中、特記がなされていない場合、記載する各種物性値、指標は、ここに記載する方法により測定、評価された値を表す。通常、複数の試料に対して、評価し、その平均値を採用している。また、含有率、濃度、配合量の表記に用いる「％」、「部」はそれぞれ質量％、質量部を表すこととする。 Various physical properties of acrylonitrile-based precursor fiber for carbon fiber and carbon fiber used in describing the present invention, specifically, “swelling degree”, “average pore radius”, “degree of orientation”, “crystal” The evaluation method will be described in advance with respect to “region size”, “strand strength, elastic modulus” and “torsional strength, elastic modulus”. In the examples, unless otherwise specified, various physical property values and indices described represent values measured and evaluated by the methods described herein. Usually, a plurality of samples are evaluated and the average value is adopted. In addition, “%” and “parts” used for notation of the content ratio, concentration, and blending amount represent mass% and mass parts, respectively.

（イ）「膨潤度」
膨潤糸を遠心脱水機を用いて付着水を除去した（毎分１８００回転を１０分間）後の質量（Ｗ）と、これを沸水洗浄してから熱風乾燥機で８０℃で１６時間乾燥した後の質量（Ｗｏ）から以下の式で求めた値である。 (I) "Swelling degree"
After removing the adhered water from the swollen yarn using a centrifugal dehydrator (1800 revolutions per minute for 10 minutes) and washing it with boiling water, and then drying it at 80 ° C. for 16 hours with a hot air dryer It is the value calculated | required by the following formula | equation from mass (Wo) of.

（ロ）「平均細孔半径」
延伸浴から出た糸条を採取し、ｔ−ブタノールと脱イオン水の混合液でｔ−ブタノールの濃度を７段階に渡り濃くした溶液に順次浸漬し、繊維構造の変化がないように糸条内の液を全てｔ−ブタノールに置換する。これを−２０℃以下に冷却しながら２４時間真空下（３Ｐａ以下）で乾燥する。この乾燥試料を約０．２ｇ精秤し、ディラトメーターに入れる。次に水銀注入装置を用いて容器内を真空（７Ｐａ以下）にし、その後水銀を充填する。そして、ポロシメーターを用いて測定を行う。圧力は最大４００ＭＰａまでかける。そして、細孔半径ｒは下式により算出される。平均細孔半径は、圧入された全水銀量の半分が圧入された時点の圧力から求められる細孔半径とした。 (B) “Average pore radius”
The yarn taken out from the drawing bath is collected and immersed in a solution in which the concentration of t-butanol is increased in seven steps with a mixed solution of t-butanol and deionized water, so that there is no change in the fiber structure. All the liquid inside is replaced with t-butanol. This is dried under vacuum (3 Pa or less) for 24 hours while cooling to −20 ° C. or less. About 0.2 g of this dried sample is accurately weighed and placed in a dilatometer. Next, the inside of the container is evacuated (7 Pa or less) using a mercury injecting apparatus, and then filled with mercury. And it measures using a porosimeter. The pressure is applied up to 400 MPa. The pore radius r is calculated by the following formula. The average pore radius was defined as the pore radius determined from the pressure at the time when half of the total amount of mercury injected was injected.

（ハ）「配向度」
数百本の炭素繊維を酢酸ビニル／メタノール溶液で固め、幅０．５ｍｍほどのサンプルを作製し、サンプルをＸ線に対して垂直な面上で３６０°回転させ、（００２）反射における最高強度を含む子午線方向のプロファイルの半価幅から下記の式を用いて配向度を算出した。Ｘ線源として、リガク社製のＣｕＫα線（Ｎｉフィルター使用）Ｘ線発生装置を用い、出力は４０ｋＶ−１００ｍＡであった。 (C) “Orientation”
Hundreds of carbon fibers are hardened with a vinyl acetate / methanol solution, a sample with a width of about 0.5 mm is prepared, the sample is rotated 360 ° on a plane perpendicular to the X-ray, and the maximum intensity in (002) reflection The degree of orientation was calculated using the following formula from the half width of the meridian profile including: As the X-ray source, a CuKα ray (using Ni filter) X-ray generator manufactured by Rigaku Corporation was used, and the output was 40 kV-100 mA.

（ニ）「結晶領域サイズ」
前駆体繊維を５０ｍｍ長に切断し、これを３０ｍｇ精秤採取し、試料繊維軸が正確に平行になるようにして引き揃えた後、試料調整用治具を用いて巾１ｍｍの厚さが均一な繊維試料束に整えた。この繊維試料束に酢酸ビニル／メタノール溶液を含浸させて形態が崩れないように固定した後、これを広角Ｘ線回折試料台に固定した。Ｘ線源として、リガク社製のＣｕＫα線（Ｎｉフィルター使用）Ｘ線発生装置を用い、同じくリガク社製のゴニオメーターにより、透過法によってグラファイトの面指数（１００）に相当する２θ＝１７°近傍の回折ピークをシンチレーションカウンターにより検出した。出力は４０ｋＶ−１００ｍＡにて測定した。回折ピークにおける半値巾から下記の式（２）を用いて、結晶領域サイズＬａを求めた。 (D) “Crystal region size”
Precursor fibers are cut into 50 mm lengths, and 30 mg of this is precisely sampled and aligned so that the sample fiber axes are exactly parallel, and then the thickness of 1 mm is uniform using a sample adjustment jig. A simple fiber sample bundle was arranged. The fiber sample bundle was impregnated with a vinyl acetate / methanol solution and fixed so as not to collapse, and then fixed to a wide-angle X-ray diffraction sample stage. As an X-ray source, a CuKα ray (using Ni filter) X-ray generator manufactured by Rigaku Corp. is used, and a goniometer also manufactured by Rigaku Corp. is used, and 2θ = around 17 ° corresponding to the surface index (100) of graphite by the transmission method. Were detected by a scintillation counter. The output was measured at 40 kV-100 mA. The crystal region size La was determined from the half width at the diffraction peak using the following formula (2).

（式中、Ｋはシェラー定数０．９、λは用いたＸ線の波長（ここではＣｕＫα線を用いているので、１．５４１８Å）、θはＢｒａｇｇの回折角、β₀は真の半値巾、β₀＝β_E−β₁（β_Eは見かけの半値巾、β₁は装置定数であり、ここでは１．０５×１０^-2ｒａｄ）である。）
（ホ）「ストランド強度、弾性率」
ＪＩＳＲ−７６０１記載の方法で測定した。ストランドの作成は、油化シェル社製「エピコート８２８（商品名）」（１００部）、無水メチルナジック酸（９０部）、ジベンジルメチルアミン（２部）、アセトン（５０部）を混合した組成の樹脂を炭素繊維に含浸後、５０℃で１時間保持し、５０℃から１３０℃に１時間かけて昇温後、１３０℃で２時間保持し硬化した。 (Where K is the Scherrer constant of 0.9, λ is the wavelength of the X-ray used (here, the CuKα ray is used, 1.5418 mm), θ is the Bragg diffraction angle, and β ₀ is the true half-width. , Β ₀ = β _E −β ₁ (β _E is an apparent half-value width, β ₁ is an apparatus constant, here 1.05 × 10 ⁻² rad).
(E) “Strand strength, elastic modulus”
It measured by the method of JISR-7601. The strand was prepared by mixing “Epicoat 828 (trade name)” (100 parts), methyl nadic acid anhydride (90 parts), dibenzylmethylamine (2 parts), and acetone (50 parts) manufactured by Yuka Shell. The carbon fiber was impregnated with carbon fiber, held at 50 ° C. for 1 hour, heated from 50 ° C. to 130 ° C. over 1 hour, then held at 130 ° C. for 2 hours and cured.

（ヘ）「単繊維ねじり強度、弾性率」
長さ約２ｍｍの単繊維試料の両端を台紙に固定し、この台紙の一端を、単繊維ねじり試験装置の金属フックに取り付けると共に、前記台紙のもう一方の端に金属フックを吊り下げ、溝のついた回転筒にセットし、回転筒を８ｍｇ／１回転にて、一定速度で回転させ、単繊維が破断したときのひずみと応力を検出することによって、単繊維ねじり強度（ＧＰａ）とねじり弾性率（ＧＰａ）を求めた。 (F) "Single fiber torsional strength, elastic modulus"
Both ends of a single fiber sample having a length of about 2 mm are fixed to a mount, and one end of this mount is attached to a metal hook of a single fiber torsion tester, and a metal hook is suspended from the other end of the mount to form a groove. It is set in a connected rotating cylinder, and the rotating cylinder is rotated at a constant speed of 8 mg / 1 rotation, and the single fiber torsional strength (GPa) and torsional elasticity are detected by detecting strain and stress when the single fiber breaks. The rate (GPa) was determined.

単繊維の試料数は２５〜３０とし、それぞれの試料について単繊維ねじり弾性率に対する単繊維ねじり強度の比を算出し、この比が０．１以上である単繊維の割合を算出した。 The number of single fiber samples was 25-30, and the ratio of single fiber torsional strength to single fiber torsional modulus was calculated for each sample, and the ratio of single fibers having this ratio of 0.1 or more was calculated.

実施例１、２、比較例１、２
アクリロニトリル９６％、メタクリル酸１％、アクリルアミド３％で共重合したアクリル系共重合体を、ジメチルアセトアミドに溶解して紡糸原液（重合体濃度２１％、原液温度６０℃）を調整した。この紡糸原液を、直径０．０７５ｍｍ、孔数６０００の口金を用いて、温度４０℃、濃度６５％のジメチルアセトアミド水溶液に吐出し凝固糸とした。 Examples 1 and 2 and Comparative Examples 1 and 2
An acrylic copolymer copolymerized with 96% acrylonitrile, 1% methacrylic acid and 3% acrylamide was dissolved in dimethylacetamide to prepare a spinning stock solution (polymer concentration 21%, stock solution temperature 60 ° C.). This spinning dope was discharged into a dimethylacetamide aqueous solution having a temperature of 40 ° C. and a concentration of 65% using a die having a diameter of 0.075 mm and a hole number of 6000 to obtain a coagulated yarn.

この凝固糸を、１．０倍、１．５倍、２．０倍というように０．５倍ごとに延伸倍率を高くしていき６．０倍までの全１２条件で７０℃、９０℃、９５℃の３段の温水中湿熱延伸を施した。６．５倍以上では繊維の破断が起こり安定に延伸できなかった。この湿熱延伸糸の膨潤度と平均細孔半径は表１にまとめ、それぞれグラフ化したものを図１、２に示す。結果、湿熱延伸倍率４．０倍で膨潤度は最大となり、延伸倍率４．５倍で平均細孔半径が最大になった。続いて、各条件の湿熱延伸糸をアミノシリコン系油剤１％水溶液中に浸漬し、１８０℃の加熱ローラーにて乾燥緻密化した。この乾燥緻密化後糸の配向度を測定した所、表１、図３のようになり延伸倍率４．５倍で乾燥緻密化後糸配向度が飽和に達することがわかった。 The coagulated yarn is increased by 0.5 times, such as 1.0 times, 1.5 times, and 2.0 times, and the draw ratio is increased every 0.5 times to 70 ° C. and 90 ° C. under all 12 conditions up to 6.0 times. , 95 ° C. three-stage warm water wet heat stretching. If it was 6.5 times or more, the fiber was broken and could not be stably stretched. The swelling degree and average pore radius of this wet heat drawn yarn are summarized in Table 1, and graphs are shown in FIGS. As a result, the degree of swelling was maximized at a wet heat draw ratio of 4.0 times, and the average pore radius was maximized at a draw ratio of 4.5 times. Subsequently, the wet heat drawn yarn of each condition was immersed in a 1% aqueous solution of an aminosilicon oil and dried and densified with a 180 ° C. heating roller. When the degree of orientation of the dried and densified yarn was measured, it was as shown in Table 1 and FIG. 3, and it was found that the degree of orientation of the yarn after drying and densification reached saturation at a draw ratio of 4.5 times.

以上の結果から、湿熱延伸倍率を２倍、３倍、５倍、６倍に設定したものをそれぞれ実施例１、２、比較例１、２とした。それぞれ上記の乾燥緻密化後、０．２５ＭＰａの加圧水蒸気中で延伸倍率が合計１２倍になるように延伸を施して、単糸繊度が１．２ｄｔｅｘ、トータル繊度が７２００ｄｔｅｘ、断面形状がほぼ円形のアクリロニトリル系前駆体繊維を得た。実施例１では、実用上全く問題にならない程度であるが、この加圧水蒸気中の延伸前の糸条が幅広になり、糸条端部の耳折れや延伸機とのこすれがあってときどき毛羽が見られた。実施例１、２、比較例１、２のアクリロニトリル系前駆体繊維の結晶領域サイズは表２のようになった。結晶領域サイズとトータル延伸倍率の関係を図４に示す。 From the above results, the wet heat draw ratios set to 2 times, 3 times, 5 times and 6 times were designated as Examples 1 and 2 and Comparative Examples 1 and 2, respectively. After each of the above-mentioned dry densification, stretching is performed in pressurized steam of 0.25 MPa so that the stretching ratio is 12 times in total, the single yarn fineness is 1.2 dtex, the total fineness is 7200 dtex, and the cross-sectional shape is almost circular. Acrylonitrile-based precursor fiber was obtained. In Example 1, there is no practical problem at all, but the yarn before stretching in the pressurized steam is widened, and there are occasional fluffing due to the ear folds of the yarn end and rubbing with the drawing machine. It was. Table 2 shows the crystal region sizes of the acrylonitrile-based precursor fibers of Examples 1 and 2 and Comparative Examples 1 and 2. The relationship between the crystal region size and the total draw ratio is shown in FIG.

得られた前駆体繊維を密度１．３５ｇ／ｃｍ²となるように空気中２３０〜２６０℃で加熱処理し耐炎化繊維とした。引き続き該繊維を窒素雰囲気中最終的に最高温度１３００℃で処理した後、硝酸中で電解処理を施し、炭素繊維を得た。ストランド強度、弾性率、ねじり強度、弾性率の結果は表３にまとめた。 The obtained precursor fiber was heat-treated in air at 230 to 260 ° C. so as to have a density of 1.35 g / cm ² to obtain a flame-resistant fiber. Subsequently, the fiber was finally treated in a nitrogen atmosphere at a maximum temperature of 1300 ° C., and then subjected to electrolytic treatment in nitric acid to obtain a carbon fiber. The results of strand strength, elastic modulus, torsional strength, and elastic modulus are summarized in Table 3.

実施例では引っ張り強度及びねじり物性の優れた炭素繊維が得られた。また、実施例１と実施例２の比較では、実施例１の方がやや強度が高くなったが、先述のように前駆体繊維の紡糸安定性が実施例２よりやや劣った。 In the examples, carbon fibers having excellent tensile strength and twisting properties were obtained. In comparison between Example 1 and Example 2, Example 1 was slightly stronger, but the spinning stability of the precursor fiber was slightly inferior to Example 2 as described above.

実施例３、比較例３
実施例１と同じ紡糸原液を、直径０．０７５ｍｍ、孔数３０００の口金を用いて、温度３５℃、濃度６０％のジメチルアセトアミド水溶液に吐出し凝固糸とした。 Example 3 and Comparative Example 3
The same spinning dope as in Example 1 was discharged into a dimethylacetamide aqueous solution having a temperature of 35 ° C. and a concentration of 60% using a die having a diameter of 0.075 mm and a hole number of 3000 to obtain a coagulated yarn.

この凝固糸を、先の例と同様に０．５倍ごとに延伸倍率を高くしていき６．０倍までの全１２条件で７０℃、９０℃、９５℃の３段の温水中湿熱延伸を施し、続いて各条件の湿熱延伸糸をアミノシリコン系油剤１％水溶液中に浸漬し、１８０℃の加熱ローラーにて乾燥緻密化した。各データを採った所、膨潤度の最大点、平均細孔半径の最大点及び乾燥緻密化後糸の配向度の飽和点はそれぞれ湿熱延伸倍率５．０倍、５．５倍及び５．５倍であった。これらの結果から、湿熱延伸倍率を３．０倍、６．０倍に設定したものをそれぞれ実施例３、比較例３とした。続いて０．２５ＭＰａの加圧水蒸気中で延伸倍率が合計１０倍になるように延伸を施して、単糸繊度が１．２ｄｔｅｘ、トータル繊度が３６００ｄｔｅｘ、断面形状が空豆形のアクリロニトリル系前駆体繊維を得た。得られたアクリロニトリル系前駆体繊維の結晶領域サイズは表２のようになった。結晶領域サイズとトータル延伸倍率の関係を図４に示す。 In the same way as in the previous example, the coagulated yarn was increased in every 0.5 times and the draw ratio was increased every 6 times up to 6.0 times in three stages of 70 ° C, 90 ° C, and 95 ° C in hot water in the wet heat. Subsequently, the wet heat drawn yarn of each condition was dipped in a 1% aqueous solution of an aminosilicon oil and dried and densified with a heating roller at 180 ° C. When each data was taken, the maximum point of the degree of swelling, the maximum point of the average pore radius, and the saturation point of the degree of orientation of the dried densified yarn were 5.0 times, 5.5 times and 5.5 times the wet heat draw ratio, respectively. It was twice. From these results, the wet heat draw ratios set to 3.0 times and 6.0 times were taken as Example 3 and Comparative Example 3, respectively. Subsequently, an acrylonitrile-based precursor fiber having a single yarn fineness of 1.2 dtex, a total fineness of 3600 dtex, and an empty bean-shaped cross-section is obtained by drawing in pressurized steam of 0.25 MPa so that the draw ratio is 10 times in total. Obtained. The crystal region sizes of the obtained acrylonitrile-based precursor fibers are as shown in Table 2. The relationship between the crystal region size and the total draw ratio is shown in FIG.

実施例１と同じ条件で焼成、電解処理を行い、炭素繊維を得た。ストランド強度、弾性率、ねじり強度、弾性率の結果は表３のようになった。実施例では引っ張り強度及びねじり物性の優れた炭素繊維が得られた。 Firing and electrolytic treatment were performed under the same conditions as in Example 1 to obtain carbon fibers. The results of strand strength, elastic modulus, torsional strength, and elastic modulus are shown in Table 3. In the examples, carbon fibers having excellent tensile strength and twisting properties were obtained.

実施例４、比較例４
実施例１と同じ紡糸原液を、直径０．０７５ｍｍ、孔数６０００の口金を用いて、温度３５℃、濃度６５％のジメチルアセトアミド水溶液に吐出し凝固糸とした。 Example 4 and Comparative Example 4
The same spinning dope as in Example 1 was discharged into a dimethylacetamide aqueous solution at a temperature of 35 ° C. and a concentration of 65% using a die having a diameter of 0.075 mm and a hole number of 6000 to obtain a coagulated yarn.

この凝固糸を、先の例と同様に０．５倍ごとに延伸倍率を高くしていき６．０倍までの全１２条件で７０℃、９０℃、９５℃の３段の温水中湿熱延伸を施し、続いて各条件の湿熱延伸糸をアミノシリコン系油剤１％水溶液中に浸漬し、１８０℃の加熱ローラーにて乾燥緻密化した。各データを採った所、膨潤度の最大点、平均細孔半径の最大点及び乾燥緻密化後糸の配向度の飽和点はそれぞれ湿熱延伸倍率４．０倍、４．５倍及び４．５倍であった。これらの結果から、湿熱延伸倍率を３．０倍、５．０倍に設定したものをそれぞれ実施例４、比較例４とした。続いて０．２５ＭＰａの加圧水蒸気中で延伸倍率が合計１０倍になるように延伸を施して、単糸繊度が０．８ｄｔｅｘ、トータル繊度が４８００ｄｔｅｘ、断面形状がほぼ円形のアクリロニトリル系前駆体繊維を得た。得られたアクリロニトリル系前駆体繊維の結晶領域サイズは表２のようになった。結晶領域サイズとトータル延伸倍率の関係を図４に示す。 In the same way as in the previous example, the coagulated yarn was increased in every 0.5 times and the draw ratio was increased every 6 times up to 6.0 times in three stages of 70 ° C, 90 ° C, and 95 ° C in hot water in the wet heat. Subsequently, the wet heat drawn yarn of each condition was dipped in a 1% aqueous solution of an aminosilicon oil and dried and densified with a heating roller at 180 ° C. When each data was taken, the maximum point of the degree of swelling, the maximum point of the average pore radius, and the saturation point of the orientation degree of the dried and densified yarn were 4.0 times, 4.5 times, and 4.5 times, respectively. It was twice. From these results, the wet heat draw ratios set to 3.0 times and 5.0 times were designated as Example 4 and Comparative Example 4, respectively. Subsequently, stretching was performed in pressurized steam of 0.25 MPa so that the stretching ratio was 10 times in total, and an acrylonitrile-based precursor fiber having a single yarn fineness of 0.8 dtex, a total fineness of 4800 dtex, and a substantially circular cross-sectional shape was obtained. Obtained. The crystal region sizes of the obtained acrylonitrile-based precursor fibers are as shown in Table 2. The relationship between the crystal region size and the total draw ratio is shown in FIG.

得られた前駆体繊維を密度１．３５ｇ／ｃｍ²となるように空気中２３０〜２６０℃で加熱処理し耐炎化繊維とした。引き続き該繊維を窒素雰囲気中最終的に最高温度１４００℃で処理した後、硝酸中で電解処理を施し、炭素繊維を得た。ストランド強度、弾性率、ねじり強度、弾性率の結果は表３にまとめた。実施例では引っ張り強度及びねじり物性の優れた炭素繊維が得られた。 The obtained precursor fiber was heat-treated in air at 230 to 260 ° C. so as to have a density of 1.35 g / cm ² to obtain a flame-resistant fiber. Subsequently, the fiber was finally treated in a nitrogen atmosphere at a maximum temperature of 1400 ° C., and then subjected to electrolytic treatment in nitric acid to obtain a carbon fiber. The results of strand strength, elastic modulus, torsional strength, and elastic modulus are summarized in Table 3. In the examples, carbon fibers having excellent tensile strength and twisting properties were obtained.

実施例５、比較例５
実施例１と同じ紡糸原液を、直径０．１５ｍｍ、孔数１５００の口金を用いて、一旦空気中に吐出し約５ｍｍの空気中を通過させた後、温度２０℃、濃度８０％のジメチルアセトアミド水溶液に導き凝固糸を得た。 Example 5, Comparative Example 5
The same spinning stock solution as in Example 1 was once discharged into the air using a die having a diameter of 0.15 mm and a number of holes of 1500 and passed through about 5 mm of air, and then dimethylacetamide having a temperature of 20 ° C. and a concentration of 80%. It was led to an aqueous solution to obtain a coagulated yarn.

この凝固糸を、先の例と同様に０．５倍ごとに延伸倍率を高くしていき６．０倍までの全１２条件で７０℃、９０℃、９５℃の３段の温水中湿熱延伸を施し、続いて各条件の湿熱延伸糸をアミノシリコン系油剤１％水溶液中に浸漬し、１８０℃の加熱ローラーにて乾燥緻密化した。各データを採った所、膨潤度の最大点、平均細孔半径の最大点及び乾燥緻密化後糸の配向度の飽和点はいずれも湿熱延伸倍率４．０倍であった。これらの結果から、湿熱延伸倍率を３．０倍、５．０倍に設定したものをそれぞれ実施例５、比較例５とした。４本合糸後、０．２５ＭＰａの加圧水蒸気中で延伸倍率が合計１０倍になるように延伸を施して、単糸繊度が１．２ｄｔｅｘ、トータル繊度が７２００ｄｔｅｘ、断面形状がほぼ円形のアクリロニトリル系前駆体繊維を得た。得られたアクリロニトリル系前駆体繊維の結晶領域サイズは表２のようになった。結晶領域サイズとトータル延伸倍率の関係を図４に示す。 In the same way as in the previous example, the coagulated yarn was increased in every 0.5 times and the draw ratio was increased every 6 times up to 6.0 times in three stages of 70 ° C, 90 ° C, and 95 ° C in hot water in the wet heat. Subsequently, the wet heat drawn yarn of each condition was dipped in a 1% aqueous solution of an aminosilicon oil and dried and densified with a heating roller at 180 ° C. When each data was taken, the maximum point of the degree of swelling, the maximum point of the average pore radius, and the saturation point of the orientation degree of the dried and densified yarn were all 4.0 times wet heat draw ratio. From these results, wet heat draw ratios set to 3.0 times and 5.0 times were designated as Example 5 and Comparative Example 5, respectively. After the four yarns are combined, they are stretched in 0.25 MPa pressurized steam so that the stretching ratio is 10 times in total. The single yarn fineness is 1.2 dtex, the total fineness is 7200 dtex, and the cross-sectional shape is an almost circular acrylonitrile system. Precursor fibers were obtained. The crystal region sizes of the obtained acrylonitrile-based precursor fibers are as shown in Table 2. The relationship between the crystal region size and the total draw ratio is shown in FIG.

得られた前駆体繊維を実施例１と同じ条件で焼成、電解処理を行い、炭素繊維を得た。ストランド強度、弾性率、ねじり強度、弾性率の結果は表３にまとめた。実施例では引っ張り強度及びねじり物性の優れた炭素繊維が得られた。 The obtained precursor fiber was baked and electrolyzed under the same conditions as in Example 1 to obtain carbon fibers. The results of strand strength, elastic modulus, torsional strength, and elastic modulus are summarized in Table 3. In the examples, carbon fibers having excellent tensile strength and twisting properties were obtained.

実施例６、比較例６
アクリロニトリル９８％、メタクリル酸２％で共重合したアクリル系共重合体を、ジメチルホルムアミドに溶解して紡糸原液（重合体濃度２３％、原液温度６０℃）を調整した。この紡糸原液を、直径０．０７５ｍｍ、孔数６０００の口金を用いて、温度３０℃、濃度５０％のジメチルホルムアミド水溶液に吐出し凝固糸とした。 Example 6 and Comparative Example 6
An acrylic copolymer copolymerized with 98% acrylonitrile and 2% methacrylic acid was dissolved in dimethylformamide to prepare a spinning stock solution (polymer concentration 23%, stock solution temperature 60 ° C.). This spinning dope was discharged into a dimethylformamide aqueous solution having a temperature of 30 ° C. and a concentration of 50% using a die having a diameter of 0.075 mm and a pore number of 6000 to obtain a coagulated yarn.

この凝固糸を、先の例と同様に０．５倍ごとに延伸倍率を高くしていき６．０倍までの全１２条件で７０℃、９０℃、９５℃の３段の温水中湿熱延伸を施し、続いて各条件の湿熱延伸糸をアミノシリコン系油剤１％水溶液中に浸漬し、１８０℃の加熱ローラーにて乾燥緻密化した。各データを採った所、膨潤度の最大点、平均細孔半径の最大点及び乾燥緻密化後糸の配向度の飽和点はいずれも湿熱延伸倍率３．５倍であった。これらの結果から、湿熱延伸倍率を２．０倍、５．０倍に設定したものをそれぞれ実施例６、比較例６とした。続いて０．２５ＭＰａの加圧水蒸気中で延伸倍率が合計１０倍になるように延伸を施して、単糸繊度が０．８ｄｔｅｘ、トータル繊度が４８００ｄｔｅｘ、断面形状がほぼ円形のアクリロニトリル系前駆体繊維を得た。得られたアクリロニトリル系前駆体繊維の結晶領域サイズは表２のようになった。結晶領域サイズとトータル延伸倍率の関係を図４に示す。 In the same way as in the previous example, the coagulated yarn was increased in every 0.5 times and the draw ratio was increased every 6 times up to 6.0 times in three stages of 70 ° C, 90 ° C, and 95 ° C in hot water in the wet heat. Subsequently, the wet heat drawn yarn of each condition was dipped in a 1% aqueous solution of an aminosilicon oil and dried and densified with a heating roller at 180 ° C. When each data was taken, the maximum point of the degree of swelling, the maximum point of the average pore radius, and the saturation point of the orientation degree of the dried densified yarn were all 3.5 times wet heat draw ratio. From these results, wet heat draw ratios set to 2.0 times and 5.0 times were designated as Example 6 and Comparative Example 6, respectively. Subsequently, stretching was performed in pressurized steam of 0.25 MPa so that the stretching ratio was 10 times in total, and an acrylonitrile-based precursor fiber having a single yarn fineness of 0.8 dtex, a total fineness of 4800 dtex, and a substantially circular cross-sectional shape was obtained. Obtained. The crystal region sizes of the obtained acrylonitrile-based precursor fibers are as shown in Table 2. The relationship between the crystal region size and the total draw ratio is shown in FIG.

実施例７、比較例７
実施例１と同じ紡糸原液を、直径０．０４５ｍｍ、孔数６０００の口金を用いて、温度３５℃、濃度６５％のジメチルアセトアミド水溶液に吐出し凝固糸とした。 Example 7 and Comparative Example 7
The same spinning dope as in Example 1 was discharged into a dimethylacetamide aqueous solution having a temperature of 35 ° C. and a concentration of 65% using a die having a diameter of 0.045 mm and a hole number of 6000 to obtain a coagulated yarn.

この凝固糸を、同様に０．５倍ごとに延伸倍率を高くしていき６．０倍までの全１２条件で７０℃、９０℃、９５℃の３段の温水中湿熱延伸を施し、続いて各条件の湿熱延伸糸をアミノシリコン系油剤１．５％水溶液中に浸漬し、１８０℃の加熱ローラーにて乾燥緻密化した。各データを採った所、膨潤度の最大点、平均細孔半径の最大点及び乾燥緻密化後糸の配向度の飽和点はそれぞれ湿熱延伸倍率３．５倍、３．５倍及び４．０倍であった。これらの結果から、湿熱延伸倍率を２．５倍、５．０倍に設定したものをそれぞれ実施例７、比較例７とした。続いて１８０℃に加熱した熱ロール間で延伸倍率が合計７倍になるように延伸を施して、単糸繊度が１．２ｄｔｅｘ、トータル繊度が７２００ｄｔｅｘ、断面形状が空豆形のアクリロニトリル系前駆体繊維を得た。得られたアクリロニトリル系前駆体繊維の結晶領域サイズは表２のようになった。結晶領域サイズとトータル延伸倍率の関係を図４に示す。 Similarly, the coagulated yarn was subjected to three-stage warm water wet heat stretching at 70 ° C., 90 ° C., and 95 ° C. under all 12 conditions up to 6.0 times while increasing the draw ratio every 0.5 times. Then, the wet heat drawn yarn of each condition was dipped in a 1.5% aminosilicone oil solution and dried and densified with a 180 ° C. heating roller. When each data was taken, the maximum point of the degree of swelling, the maximum point of the average pore radius, and the saturation point of the orientation degree of the dried densified yarn were 3.5 times, 3.5 times and 4.0 times the wet heat draw ratio, respectively. It was twice. From these results, wet heat draw ratios set to 2.5 times and 5.0 times were designated as Example 7 and Comparative Example 7, respectively. Subsequently, stretching is performed between hot rolls heated to 180 ° C. so that the stretching ratio becomes 7 times in total, and the single fiber fineness is 1.2 dtex, the total fineness is 7200 dtex, and the cross-sectional shape is an acrylonitrile-based precursor fiber. Got. The crystal region sizes of the obtained acrylonitrile-based precursor fibers are as shown in Table 2. The relationship between the crystal region size and the total draw ratio is shown in FIG.

得られた前駆体繊維を実施例４と同じ条件で焼成、電解処理を行い、炭素繊維を得た。ストランド強度、弾性率、ねじり強度、弾性率の結果は表３にまとめた。実施例では引っ張り強度及びねじり物性の優れた炭素繊維が得られた。 The obtained precursor fiber was baked and electrolyzed under the same conditions as in Example 4 to obtain carbon fibers. The results of strand strength, elastic modulus, torsional strength, and elastic modulus are summarized in Table 3. In the examples, carbon fibers having excellent tensile strength and twisting properties were obtained.

実施例における湿熱延伸倍率と湿熱延伸糸膨潤度との関係を示すグラフである。It is a graph which shows the relationship between the wet heat draw ratio and wet heat draw yarn swelling degree in an Example. 実施例における湿熱延伸倍率と平均細孔半径との関係を示すグラフである。It is a graph which shows the relationship between the wet heat draw ratio and average pore radius in an Example. 実施例における湿熱延伸倍率と配向度との関係を示すグラフである。It is a graph which shows the relationship between the wet heat draw ratio and orientation degree in an Example. 実施例におけるトータル延伸倍率と結晶領域サイズとの関係を示すグラフである。It is a graph which shows the relationship between the total draw ratio and crystal region size in an Example.

Claims

The crystal region size obtained from the (100) reflection of polyacrylonitrile of the resulting precursor fiber, and the total draw ratio is a method for producing acrylonitrile-based precursor fiber for carbon fiber,

A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, It has a drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the draw ratio when the wet heat draw yarn swelling degree is the maximum value or less A method for producing acrylonitrile-based precursor fiber for carbon fiber.

A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, It has a drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the draw ratio when the wet heat draw yarn swelling degree reaches the saturation point or less A method for producing acrylonitrile-based precursor fiber for carbon fiber.

A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, a dry densification process of drying densified yarn treated oil agent, the total draw ratio 12 times or less, the wet heat stretching ratio, average pore radius at which becomes a maximum value of 3 times or more and wet heat drawn yarn The manufacturing method of the acrylonitrile type | system | group precursor fiber for carbon fibers made into a draw ratio or less.

A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, A drying densification step of drying and densifying the oil-treated yarn, a total draw ratio of 12 times or less, a wet heat draw ratio of 3 times or more, and an average pore radius of the wet heat draw yarn reaches a saturation point The manufacturing method of the acrylonitrile type | system | group precursor fiber for carbon fibers made into a draw ratio or less.

A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, A drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the fiber orientation degree immediately after the dry densification becomes the maximum value The manufacturing method of the acrylonitrile type | system | group precursor fiber for carbon fibers made into a draw ratio or less.

A spinning step of spinning a spinning stock solution containing a solvent and an acrylonitrile-based polymer dissolved in the solvent to obtain a coagulated yarn, a wet heat drawing step of subjecting the coagulated yarn to wet heat drawing, an oil agent treatment step of treating the drawn yarn with an oil agent, A drying densification step of drying and densifying the oil-treated yarn, the total draw ratio is 12 times or less, the wet heat draw ratio is 3 times or more, and the fiber orientation degree immediately after the dry densification reaches the saturation point The manufacturing method of the acrylonitrile type | system | group precursor fiber for carbon fibers made into a draw ratio or less.

The acrylonitrile-based precursor fiber for carbon fiber according to any one of claims 1 to 6 , wherein the solvent is dimethylacetamide or dimethylformamide, and the wet-heat drawn yarn swelling degree when performing the wet-heat drawing is 120% or less. Manufacturing method.